In recent years, the mainstream of streaming services utilizing the Internet has been OTT-V (Over The Top Video), and as a globally standardized moving picture delivery protocol that can be used for it, there is known the MPEG-DASH (Moving Picture Experts Group-Dynamic Adaptive Streaming over HTTP, hereinbelow called DASH), which uses HTTP similar to the browsing of websites and the like (for example, refer to Non-Patent Literature 1).
In DASH, adaptive streaming technology is achieved. That is to say, on the content supply side, multiple streams of the same content but whose bit rates differ by differences in image quality and field angle size are prepared and delivered. On the other hand, the reception side can select, receive and play back the optimum stream in accordance with the Internet communication environment its own decoding capability, and the like among the plurality of streams the supply side has prepared.
Metafiles called MPD (Media Presentation Description) are supplied from the supply side to the reception side so that the reception side can adaptively select, receive, mid play back streams.
The address (url information) of the server supplying streams of chunked content (media data such as Audio/Video/Subtitle) is described in the MPD. The reception side, based on the url information, accesses the server that is the supply source of fee content to request a stream, receives the stream delivered over HTTP unicast from the server m accordance with the request, and plays it back.
FIG. 1 shows an example of the constitution of a content supply system that streams contest based on DASH.
This content supply system 10 is constituted from a plurality of content supply devices 20 that supply content and a plurality of DASH clients 30 that receive and play back content. The DASH client 30 is connected to the content supply device 20 via a CDN (Contents Delivery Network) 12 that utilizes the Internet 11.
The content supply device 20 delivers a plurality of streams having the same content but different bit rates. The contest supply device 20 has a content management server 21, a DASH segment streamer 22, and a DASH MPD server 23.
The content management server 21 manages the source data of content for delivery to the DASH client 30, generates a plurality of streaming data of different bit rates from the source data and outputs them to the DASH segment streamer 22.
The DASH segment streamer 22, by dividing each streaming-data temporally into segments, to generate a segment stream such as Fragmented MP4 and the like, and files and holds the generated segment stream. Moreover, the DASH segment streamer 22, as a WEB server, in accordance with a request (HTTP request) from the DASH client 30, delivers over HTTP unicast the file of the segment stream it holds to fee request source. Furthermore, the DASH segment streamer 22 notifies the DASH MPD server 23 of metadata including the address expressing fee supply source of the segment stream file.
The DASH MPD server 23 generates an MPD containing an address or the like indicating the supply source (that is, the DASH segment streamer 22) of the segment stream file. Also, the DASH MPD server 23, as a WEB server, is accordance with a request (HTTP request) from the DASH client 30, delivers over HTTP unicast the generated MPD to the request source.
The DASH client 30 requests the MPD from the DASH MPD server 23, and in response, receives the MPD delivered over HTTP unicast. Moreover, the DASH client 30, based on the received MPD, requests a segment stream file from the DASH segment streamer 22, and in response receives and plays back the segment stream file that is delivered over HTTP unicast.
Note that the CDN 12 includes a caching server (not illustrated), and the caching server caches the MPD and segment stream file delivered over HTTP unicast via the CDN 12. The caching server, instead of the DASH MPD server 23 or the DASH segment streamer 22 as WEB servers, can deliver over HTTP unicast the cached MPD and segment stream file to the DASH client 30 of the request source.